Taking a large diffusion pump apart.

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Justin Fozzard
Posts: 54
Joined: Thu Aug 24, 2017 7:11 am
Real name: Justin Fozzard
Location: Essex, England

Taking a large diffusion pump apart.

Post by Justin Fozzard »

Hello and Happy New Year to you all.

I wonder if anyone on the forum has dismantled an Edwards E012 diffusion pump? It’s rather large at 12” diameter and so far I have been a bit stumped as to how to take it apart for cleaning. The pump is for use with a large vacuum chamber that I hope to use for some magnetised plasma experiments.

Edwards E012
Edwards E012 Diffusion Pump.jpeg

Vacuum Chamber and Baffle Valve
Vacuum Chamber and Baffle Valve.jpeg

I’ve removed the spider holding the jet stack centrally and have tried to unscrew the stack, but the whole upper stack just turns and it feels as though the jets are held together by springs. A jet pointing through the side exhaust port is also preventing the lower stack from turning and lifting out.

Spider
Edwards E012 Diffusion Pump Spider.jpeg

I tried unscrewing the aluminium top jet from the second jet with a strap-wrench and also carefully tried to pull it from the jet with a pulley-puller without any luck. The top jet has a steel rod running through it and a spring sits between it and the spider as seen in this photo:

Top Jet Cap
Edwards E012 Diffusion Pump Christmas Tree.jpeg

I don’t want to force anything apart in case I stretch the springs or damage the thin sheet steel jets.

I have noted that some newer large Edwards pumps have a threaded rod holding the jet stack, but my pump seems to be assembled differently.

Does anyone have any suggestions, or a manual for an Edwards E012, please?

Many thanks,

Justin Fozzard
Jerry Biehler
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Joined: Tue Nov 24, 2009 3:08 am
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Location: Beaverton, OR

Re: Taking a large diffusion pump apart.

Post by Jerry Biehler »

It's probably just glued into the base from years of gunked DP oil.
Justin Fozzard
Posts: 54
Joined: Thu Aug 24, 2017 7:11 am
Real name: Justin Fozzard
Location: Essex, England

Re: Taking a large diffusion pump apart.

Post by Justin Fozzard »

Thanks for your advice, Jerry, you were right.

The aluminium top jet was stuck by oily gunk to the lower one and after some very careful tapping with a rubber hammer it simply popped off.
The lower jets were held in by a screwed rod and quickly came apart so I can now start cleaning away the old oil residues.

Regards,
Justin Fozzard
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